Laser device and exposure method

Abstract

A laser device which can be used as a light source for an exposure device, can be downsized, and is easy to maintain. A laser beam (LB6) emitted from a DFB (Distributed feedback) semiconductor laser, for example, and amplified by an optical fiber amplifier is passed through non-linear optical crystals (502, 503, 504) to be sequentially doubled in frequency to thereby generate an ultraviolet-region laser beam (LB5) consisting of an octuple wave. A GdYCOB, that is, GdxY1−xCa4O(BO3)3 crystal (0≦×≦1) is used for the non-linear optical crystal (503) for a double wave-to-quadruple wave conversion, and a KAB, that is, K2Al2B4O7 crystal for the non-linear optical crystal (504) for a quadruple wave-to-octuple wave conversion. The non-linear optical crystals (502-504) are all fine-tuned in phase match angle by temperature controllers (521-523) respectively.

Description

[0001]This application is the international phase under 35 U.S.C. 371 of prior PCT International Application No. PCT / JP00 / 06131 which has an International filing date of Sep. 8, 2000 which designated the United States of America, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD[0002]The present invention relates to a laser device that generates ultraviolet light and an exposure method using this device. More specifically, the present invention is preferably used as, for example, an exposure light source or a measuring light source of an exposure apparatus used in a photolithography process for manufacturing microdevices, such as semiconductor devices, image pickup devices (such as CCDs), liquid crystal display devices, plasma display devices, and thin-film magnetic heads.BACKGROUND ART[0003]For example, an exposure apparatus used in a photolithography process for manufacturing a semiconductor integrated circuit optically reduces and projectively expo...

AI Technical Summary

Benefits of technology

[0019]The laser divice in each of the above-described aspects of the present invention allows use of a light source which is small and which has a narrow oscillatory spectrum such as, for example, a distributed feed back (DFB) semiconductor laser controlled in oscillation wavelength or a fiber laser. High-output mono-wavelength ultraviolet light which has a narrow spectral width can be obtained in the following manner. A mono-wavelength laser beam output from the laser generator section is amplified using the optical fiber amplifier; and thereafter, the laser light is converted into ultraviolet light through the nonlinear optical crystal. As such, the present invention enables the provision of the laser device which is small and which has high maintainability.

[0037]Moreover, in the exposure method of the present invention ultraviolet light from the laser device of the present invention is incident onto a mask, and a substrate is exposed with the ultraviolet light passed through a pattern of the mask. The exposure apparatus of the present invention uses the laser divice of the present invention as an exposure light source, and includes an illumination system which irradiate a mask with ultraviolet light from the laser device, and a projection optical system which projects an image of a pattern of the mask onto a substrate, wherein the substrate is exposed with the ultraviolet light passed through the pattern of the mask. With the laser device of the present invention being used, the exposure apparatus can be miniaturized overall, and the maintainability thereof is increased.

Problems solved by technology

Second, when the exposure light is ultraviolet light having a wavelength of 300 nm or shorter, an optical material which can be used for a reflector member (lens) of a projection optical system is limited, and hence the difficulty increases for compensation of the chromatic aberration.

This arises various problems.

For example, the transmittance of an optical component tends to vary because of so-called compaction and the like, complicated maintenance is required and costs are increased.

In this connection, these methods arises other problems.

For example, the aforementioned adjustment requires a sensitive arrangement; and in proportion to the increase in the constituent laser elements, the complexity of the configuration needs to be increased to cause the overall devices to oscillate with the same wavelength.

However, the method has problems in that it requires an optical system for separating the seed light into the individual laser elements and an oscillatory-wavelength tuning control section, thereby increase complexity of the configuration.

In addition, the array laser as described above enables the overall device to be significantly smaller than that with the conventional excimer laser, it still causes difficulty in packaging so as to reduce the diameter of overall arrayed output beams to several centimeters or smaller.

The array laser thus configured has additional problems.

For example, each of the arrays requires the wavelength conversion section, thereby increasing the cost.

In addition, suppose misalignment has occurred in a part of the laser elements constituting the array, or damage has occurred with the constituent optical elements.

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